We’re going to figure out the cost to buy and operate lights that emits 1600 lumens for 20000 hours given that energy costs 2:

Traditional Incandescent
Cost of energy:

Cost of bulbs:

Total Cost:

You can do the same math for the rest of the bulbs (substituting the proper numbers in) to get a chart that looks like this:

TraditionalIncandescent

HalogenIncandescent

CompactFluorescent (CFL)

LED

Watts (W)

100

77

23

20

Lumens (lm)

1600

1600

1600

1600

Cost/bulb

$0.37

$1.59

$2.23

$45

Life span (hours)

750

1000

10000

20000

W/lm

0.0625

0.0481

0.0144

0.0125

$/(lm-h)

5.313E-06

4.091E-06

1.222E-06

1.063E-06

Cost to run

$170.00

$130.90

$39.10

$34.00

$/h

0.493E-04

1.590E-04

2.230E-04

2.250E-04

Cost to buy

$9.87

$31.80

$4.46

$45.00

Total cost

$179.87

$162.70

$43.56

$79.00

Here’s the thing I found amazing: there’s a big push to implement LEDs, probably because of the ‘cool’ factor. However, they don’t save that much more energy over CFL — about 13% — and they cost almost twice as much to operate right now. Manufacturers are going to have to have to drop the cost of LED lights a lot in order to make a change worth it…or the government will have to ban mercury in lights3.

Graphic by George Retseck and Jen Christiansen
Sources: U.S. Department of Energy and Efficacy calculations based on currently available bulbs (traditional, halogen and compact fluorescent); SWITCH LIGHTING (led)

All content by Andrew Ferguson unless otherwise noted, with some restrictions on its use. For anyone who cares, this weblog does not represent the thoughts, intentions, plans or strategies of my employer and/or school. It is solely my opinion, sorry. If you've reached this point, I'll assume you have time to kill, trying reading a random blog post.